In Great Britain April 17, 1940 I 6 Claims. (01. 18-54) I This invention relates to the manufacture of It is to be understood that, for the purpose of the artificial textile materials and the like and parpresent specification, the term dry-spinning ticularly to materials having a basis of synthetic process" covers a melt-spinning process in which thermoplastic materials of high molecular weight. setting takes place in a gaseous or vaporous at- It has recently been found that synthetic filmo mosphere.

or fibre-forming substances may be produced by Materials spun according to the dry-spinning the union of the residues of the molecules of process in which the extruded materials are first one or more reagents, each containing two rereceived in an enclosed chamber, such as isv necactive groups in the molecule, by the condensaessary when operating upon molten polymers of tion of a reactive group of one molecule with a lo the .type described above, may be collected in reactive group of another molecule, water, hydroeither of two ways, viz., inside or outside the chloric acid or a similar substance being elimspinning chamber. If the former method is inated during the reaction. Synthetic substances adopted, it is necessariflto open the chamber at or polymers of this nature may be formed, for relatively frequent intervals to attend to the example, by condensing diamine with dicarboxl winding devices, while if the latter method is ylic'acids, with dihalogen derivatives of hydroemployed, an opening must be provided for the carbons, with 'disulphonic acids or with glycols, withdrawal of the products and this opening renamino-carboxylic acids, amino-sulphonic acids, ders it difiicult, if not impossible, to avoid entry or amino-halides with themselves or with each of air which may contact with and damage the other, diacid amides with diacids, and so forth. 20 highly heated materials. Of these two methods,

'By a suitable choice of reagents, it is possible to the second is by far the prefera l provided that produce substances with long chain molecules some Way Of eeti t d y ntioned of high molecular weight which can be converted can be devised.

by suitable methods intofibres or films. Prefer- I have now found that the dry-spinning operably reagents are chosen which have no substanation can be successfully app d to m l n p0ly-. tial tendency-to condense with formation of cyclic mers or to molten compositions containing the compounds. This may be achieved by selecting polymers, without the necessity of preventing enthe reagents in such away that the unit length try of air into the chamber through the opening of the resulting polymer consists of more than provided for the withdrawal of the products, by 6 atoms in a chain, and preferably more than 7 3o drawi g O the atmosphere of the chamber at atoms. In the case of condensing diamines with one or more regions situated between the spindicarboxylic acids, for example, the unit length ning orifices d the said opening. In this way is arrived at b adding the numbe of atoms there is formed in the chamber a zone which is joining the two nitrogen atoms in the diames substantially filled with inert medium and in plus 2, .to the number of atoms joining the carwhich the filaments or other materials are reboxylic groups in the dicarboxylic acids plus 2. ceived on extrusion, and another zone which is Th filmor fibre-forming polymers resulting substantially filled with air and from which the from such condensatlons may be formed into filaments are withdrawn from the chamber. The textile filaments, bristles, ribbons, films and the extent of these two zones is determined so that like, and in order to do so it is frequently consufficient cooling of the extruded materials takes venient to work at rather high temperatures, e. g. place in the inert medium to allow for their conof the order of ZOO-300 C. For example, shaped tact with air without risk of damage to the maarticles may be formed from polymers or soluterials. a

tions of polymers in appropriate solvents by According to the invention, therefore, artificial shaping them in molten condition, but often the textile materials and the like are produced by polymers or solutions only become sufnciently extruding fluid material compri a synthetic fluid for extrusion or other-shaping operation at th r p ast hi h y polymeric fi r -f rmin temperatures of 2Q0-300? C. -At such tempera- Substance t a inert g s or vaporous metures however, and even t lower temperatures dium, coolingthe extruded material in the said than these, exposure of the polymer to oxygenmedium to a temperature atwhich air has subcontaining gases is liable to leadto discoloration stantially no damaging efiect on the material, of the materials. For this reason, it has been and thereafter introducing thematerial into'air proposed to employ nitrogen or some other inert and completing the setting thereof. The invengaseous medium as the setting atmosphere when. tion also includes'apparatus by which this. procworklng according to the dry-spinning process. 56 essmay be carried out.

The nature of the invention will be more clearly understood by reference to particular apparatus for use in spinning from a mass of molten polymer. Figures 1 and 2 of the accompanying drawing show, by way of example, two formsof apparatus according to the invention.

In Figure 1, a narrow tube 3surrounded by an electric heating element 4 is mounted in the upper end of a cylindrical casing 5 enclosing a chamber 6, and feeds molten material to a spinning jet 1 which is closely surrounded by an electric heating-element 8 to maintain the face of the jet and the closely adjacent atmosphere at a desired elevated temperature. Filaments 9, extruded from the jet 1, pass down the chamber 6 to a guide bar [0 and thence through a small opening II to a feed roller l2 and a suitable winding, twisting and winding, or other take-up device, not shown. The upper part of the chamber 6 is fed with an inert gas or vapour from a lead l3, through holes M in an annular pipe l5. This inert gas or vapour is drawn off from the chamber through holes IS in an annular pipe H, to a suction pipe [8. The annular pipe I! is situated at such a distance from the jet 1 that the filaments 9 before they reach the level of the pipe have cooled sumciently to be substantially undamaged by contact with air. The suction applied through the holes l6 also draws air into the lower partof the chamber 6, through the circular hole l9 covered with fine wire gauze in the base of the casing 5. A small amount of air also enters through the opening I I. A diaphragm 2|, mounted between the annular pipe H and the casing 5, prevents the passage of gases or vapours through this space, and electric heating elements 22 on the inside of the casing 5 can be employed for heating the atmosphere in the chamber 6.

In Figure 2, a narrow tube 23 surrounded by an electric heating element .24 is mounted in the upper end of a rectangular casing 25 enclosing a chamber 26, and feeds molten material to a spinning jet 2'! which is closely surrounded by an electric heating element 28 to maintain the face of the jet and the closely adjacent atmosphere at a desired elevated temperature. Filaments 29, extruded from the jet 21, pass down the chamber 26 to a guide 30 and thence through an orifice 3| in the base of the casing 25, to a feed roller 32 and a suitable winding, twisting and winding, or other take-up device, not shown. The upper part of the chamber 26 is fed with an inert gas or vapour passing from a lead 33 and orifices 34 through fine wire gauze 35 into the chamber and out through fine wire gauze 36 and orifices 31 to the suction pipe 38. Some part of the inert gas or vapour is drawn off from the chamber through holes 39 in an annular pipe 40 to a suction pipe 4|, and the same means also draws air in through the orifice 3| and up through the lower part of the chamber 26. The

' be applied to the apparatus shown in the other figure with appropriate modification, and that other modifications may also be made. For example, inlets and outlets for inert gas or vapour chamber.

similar to those shown in Fig. 2 may be employed in conjunction with cylindrical or other casings as well as with rectangular casings, and an inlet pipe of the type illustrated at l5 in Figure 1 may be employed in casings which are not cylindrical. Electric heating elements as at 22 may also be included in the apparatus of Figure 2. In place of electric heating elements, coils may be provided so that the spinning chambers may be either heated or cooled by appropriate fluids according to the desired speed of setting of the extruded materials. Although at 20, 35 and 36 only a single wire gauze sheet is shown, it may be desirable, particularly at 20 and 35, in order to produce better parallelisation of the flow of gases or vapours, to employ a pair of sheets of gauze spaced apart about or even more. One or two sheets of gauze may'also be provided just below the inlet for inert gas or vapour in Fig. 1 so that the flow of this medium past the jet may be substantially parallel.

The drawing shows only one spinning jet in a particular casing, but there may be a number of jets in a casing, arranged, for example, in line. The necessary modification of the details of the apparatus will be obvious if such a number of jets are to be employed.

The actual extent of the zone of inert medium substantially free from air will naturally depend upon a number of factors, including the nature of the polymer, particularly as regards its specific heat and the maximum temperature at which it is stable to air, the temperature of extrusion, and the cross-section of the materials. It may extend, for example, for one to two or three feet or more from the face of the spinneret.

The inert medium is advantageously a vapour which can readily be recovered from admixture with the air with which it is drawn ofi from the It is generally undesirable that such a vapour should condense in the chamber itself and it should therefore be the vapour ofa liquid of relatively low boiling point. Suitable agents are, for example, ethyl ether, dioxane, ethyl chloride and carbon tetrachloride. Steam may also be employed, with particular advantage. Other media which may be employed are inert gases such as, for example, nitrogen, carbon dioxide, preferably well dried, and hydrogen. If desired, the inert gases or vapours may be preheated to a temperature substantially above atmospheric temperature or above their condensation temperature, before being introduced into the chamber, but this is not generally necessary, though it is advantageous to introduce a separate supply of preheated medium into the immediate neighbourhood of the spinneret at a temperature approaching that of the molten material to be extruded.

The present invention is of the greatest importance in connection with the extrusion of molten polymers or molten compositions containing the polymers substantially free from vol atile agents so that the operation of setting consists in simply cooling the molten materials below their point of fusion. However, other compositions may be employed, especially compositions containing volatile solvents or other softening agents for the polymers such as, for example, phenols, e. g. phenol, cresol and xylenol. When shaping-such compositions according to the process of the present invention, the volatile softening agent may be evaporated, at least in part, from the extruded materials during passage through the inert medium so that setting takes place in this medium by the combined effect of cooling and removal of solvent. Further evaporation of volatile agent may, if desired, be ef fected by means of the air present in the lower part of the chamber.

I Alternatively, residual softening agent may be removed by washing in a suitable bath of non-solvent for. the polymer. Instead of evaporating any substantial amount of volatile softening agent from the extruded materials, the whole may be removed by washing the materials after they have been withdrawn from the spinning chamber.

For the purposes of the present invention, the jet may be supplied with material from any suitable source of molten material. For example, the jet may be fed with molten material which has been brought to a uniform degree of fluidity by feeding through a narrow tube, as described in my U. S. application S. No. 375,762, filed J anuary 24, 1941, under pressure applied by means of pumps of which at least the glands are immersed in a heated fiuid medium which is a non-solvent for the material as described in my U. S. application S. No. 375,761, filed January 24, 1941.

Shaped materials according to the invention may,have the form of filaments, yarns, films,

foils or other shaped articles formed by extrusion or like methods, and the filamentary products may be converted, if desired, into staple fibre, for example by cutting methods. If desired, various effects may be produced in the articles by modifying the composition of the fused material to be extruded. Such effect materials maybe, for example, high-boiling softening agents, which are preferably insoluble in the inert nonsolvent medium, pigments, dyes and the like. Such effect materials may be introduced into the reaction mixture before polymerisation takes .place, or during polymerisation, or after completion of the polymerisation. In addition to, such effect materials, the characteristics of the products may be modified by. incorporating in the fused materials, one or more other thermoplastic substances for example organic derivatives of cellulose, e. g. cellulose acetate, cellulose aceto-propionate, cellulose acetobutyrate, cellulose stearate or cellulose acetostearate. Such additional thermoplastic materials may, in particular, modify the dye affinity of the products as well as the general physical characteristics thereof.

Having described my invention, whatI desire to secure by Letters Patent is:

1. Process for the production of artificial textile materials and the like, which comprises extruding a fluid material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature at which air has a damaging effect on the said substance into a chamber of which the zone into which the material is extruded is filled with an inert gaseous or vaporous medium which is fed thereto and has a cooling effect on said material, passing the extruded material, after it is cooled to a temperature at which air has substantially no damaging effect on the substance, from the said zone to a zone which is filled with air and to which air is admittedjwithdrawing a mixture of said inert medium and air from the chamber at the common boundary of the two zones,

and withdrawing the material ,from the said truding a fluid material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature. at which air has a damaging effect on the said substance into a chamber of which the zone into which'the ma- .terial is extruded is filled with an inert gaseous or vaporous medium which is fed thereto, a por- 'tion of said medium immediately surrounding the extruded material during the early stage of a mixture of said inert medium and air from the chamber at the common boundary of the two zones, .and withdrawing the material from the said chamber. v

. 3. Process for the production of artificial textile materials and the like, which comprises extruding a fiuid material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature at which air has a damaging effect on the said substance into a chamber of which the zone into which the material is extruded is filled with a medium comprising the vapor of a liquid of relatively .low boiling point which can readily be recovered from admixture with air, which medium is fed to said zone and has a cooling effect on said material, passing the extruded material, after it is cooled to a temperature at which air has substantially no damaging effect on the substance, from the said zone to a zone which is filled with air and to which air is admitted, withdrawing a mixture of said inert medium and air from the chamber at the common boundary of the two zones, and Withdrawing the material from the said chamber.

'4. Process for the production of artificial textile materials and the like, which comprises extruding a fiuid material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature at which air has a damaging effect on the said substance into a chamber of which the zone into which the material is extruded is filled with a medium comprising the vapor of a liquid of relatively ,low boiling point which can readily be recovered from admixture with air, which medium is fed to said zone, a portion of said medium immediately surrounding the extruded material during the early stage of its travel in said medium being heated to substantially the same temperature as that of e the fluid material at the time of extrusion and the remainder of said medium being at a ternperature which has a cooling effect on the extruded material, passing the extruded material, after it is cooled to a temperature at which air has substantially no damaging effect on the substance, from the said zone to a zone which is filled with air and to which air is admitted, withdrawing a mixture of said inert medium and air from the chamber at the common boundary of the two zones, and withdrawing the material from the said chamber.

5. Process for the production of artificial textile materials and the like, which comprises extruding a fluid. material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature at which air has a damaging effect on the said substance into a chamber of which the zone into which the material is extruded is filled with steam which is fed thereto and has a cooling effect on said material, passing the extruded material, after it is cooled to a temperature at which air has substantially no damaging effect on the substance, from the said zone to a zone which is filled with air and to which air is admitted, withdrawing a mixture of steam and air from the chamber at the common boundary of the two zones, and withdrawing the material from the said chamber.

6. Process for the production of artificial textile materials and the like, which comprises extruding a fluid material comprising a synthetic thermoplastic highly polymeric fibre forming substance at a temperature at which air has a damaging effect on the said substance into a chamber of which the zone into which the material is extruded is filled with steam which is air and to which air is admitted, withdrawing a mixture of steam and air from the chamber at the common boundary of the two zones, and withdrawing the material from the said chamber.